Synthesis of novel steroids bearing a spirochromene side chain by BF3·Et2O catalyzed aldol condensation of spirostane sapogenins and salicylaldehyde

Treatment of a CH2Cl2 solution of sarsasapogenin acetate with salicylaldehyde and BF3·Et2O afforded a mixture of two C-22 epimeric steroids bearing a spirochromene moiety in the side chain. The elucidation of the structures of the new compounds were carried out employing a combination of 1D and 2D NMR techniques that includes 1H, 13C, HSQC, HMBC, COSY and NOESY.